PB2101: A PROSPECTIVE INVESTIGATION INTO THE TIMING AND STATUS OF BCMA-CART IN SECONDARY PLASMA CELL LEUKEMIA
Authors: Yuelu Guo, Kai Hu, Xiaoyan Ke, Fan Yang, Lixia MA, Teng Xu, Liu Rui, Zhonghua Fu, Peihao Zheng, Shaomei Feng, Hui Shi, Biping Deng
Journal: HemaSphere (2023)

Topic: 14. Myeloma and other monoclonal gammopathies - Clinical Background: sPCL are found in relapsed/refractory MM (RRMM) with multiple lines of disease progression, The use of BCMA-CART in multiple myeloma has extended survival for many patients, but it is less commonly studied in sPCL. Aims: To assess the efficacy and safety of BCMA-CART in patients with secondary plasma cell leukemia(sPCL), as well as to investigate the consolidation regimen and timing of application in patients who achieved PR after CART. Methods: Patients with sPCL who met the entry criteria were enrolled and treated with BCMA-CART after lymphatic clearance pretreatment regimens, with some patients later receiving allogeneic transplantation(Allo-SCT) for consolidation, to assess the efficacy and safety of this treatment. Results: A total of 8 patients with sPCL were included in our study center from 2020.12 to 2022.11, with a male proportion of 6/8 (75%); 4/8 (50%) patients <45 years old, median age was 48.5 years; 8 patients had DS stage III, with 7/8 (87.5%) in group A; 3/8 (37.5%) were in ISS andR-ISS stage II,5/8 (62.5%) were in ISS and R-ISS stage III; mSMART3.0 stage were all in the high-Risk group, with Double Hit Myeloma accounting for 5/8 (62.5%); only 1 patient with extramedullary lesions; median CPC and range were 22% (6%-77%) respectively; proportion of previous treatment lines 5 (62.5%) and median line 3.5 (1-7); 8/8 (100%) patients were all resistant to lenalidomide, 4/8 (50%) were resistant to pomalidomide, 8/8 (100%) were all resistant to bortezomib, 2/8 (25%) were resistant to carfilzomib, and 8/8 (100%) were all resistant to daratumumab; only 3/8 (37.5%) patients had SCT history.The median and range of peak BCMA-CART amplification was 16 (11-28) days; the best outcome after BCMA-CART was PR in 6 patients, with ORR at 1 and 2 months after CART being 6/ 8 (75%) 4PR,2VGPR.Three of the six patients who achieved remission underwent Allo-SCT for consolidation therapy three months after CART, two patients are still alive with sCR, and one patient relapsed and died one month after consolidation therapy with Allo-SCT; the other three patients did not undergo Allo-SCT and consolidation therapy with CART for financial and medical reasons, and one relapsed and died 6 months after CART, one relapsed and died 1 year and 3 months after CART, and one is still alive. One case died after a one year and 3 months after CART relapse. and one case is still in the VGPR follow-up phase;The median follow-up time was 186.5 days, and the 6-month PFS and OS rates were 62.5% and 60%, respectively. BCMA-CART treated CRS Grade 1 ratio was 4/8(50%), Grade 2 was 2/8(25%), Grade 4 was 2/8(25%); all 8 patients had no ICANS; anemia Grade3 was 8/8(100%), neutropenia Grade2 was 1/8(12.5%), Grade3 was 7/8(87.5%), thrombocytopenia Grade3 was 1/8(12.5), Grade4 was 7/8(87.5%);nausea/vomiting Grade 1 was 4/8 (50%) and Grade 3 was 4/8 (50%); two patients died within one month of returning to CART due to severe pneumonia and gastrointestinal haemorrhage; two patients who died early had up to 70% abnormal peripheral blood plasma cells; and one patient developed pulmonary Aspergillus infection three months after returning to CART. Summary/Conclusion: BCMA-CART therapy can provide short-term relief for patients with sPCL, It is recommended that patients who achieve PR after CART undergo Allo-SCT for consolidation therapy as soon as possible to obtain deep remission and achieve long-term survival.Keywords: Multiple myeloma, Allo-SCT, CAR-T, B-cell maturation antigen